Flavonoids from <em>Cyclocarya paliurus</em>: Extraction, Antioxidant Activity, and Promotion of Osteogenic Differentiation in MC3T3-E1 Cells

In this study, four types of macroporous resins (HPD-600, AB-8, D-101, and DM130) and a polyamide resin were compared the efficiency to extract total flavonoids from Cyclocarya paliurus (Batal.) Iljinskaja (CPF). Among them, HPD-600 was identified as the most effective. The ideal adsorption conditions were determined to be as follows: 70% ethanol used as the eluent, a flow rate of 2 BV/h, and a CPF concentration of 1.0 mg/mL. Following purification with HPD-600, the CPF yield increased to 69.76% ± 2.3%. Purified CPF exhibited strong ABTS⁺ radical scavenging activity. Furthermore, in CPF-treated MC3T3-E1 cells, the osteogenic proliferation and differentiation activity were evaluated. At a concentration of 200 μg/mL, CPF enhanced cell viability, not affecting cell proliferation by Ki67 staining. CPF promoted osteogenic differentiation by ALP staining. In mechanism, CPF enhanced osteogenic differentiation by PI3K-AKT-FOXO1 signaling pathway.